American journal of physiology. Cell physiology最新文献

We aimed to study transcriptional and phenotypic changes in circulating immune cells associated with increased risk of mortality in COVID-19, resolution of pulmonary fibrosis in post-COVID-19-interstitial lung disease (ILD), and persistence of idiopathic pulmonary fibrosis (IPF). Whole blood and peripheral blood mononuclear cells (PBMCs) were obtained from 227 subjects with COVID-19, post-COVID-19 interstitial lung disease (ILD), IPF, and controls. We measured a 50-gene signature (nCounter, Nanostring) previously found to be predictive of IPF and COVID-19 mortality along with plasma levels of several biomarkers by Luminex. In addition, we performed single-cell RNA sequencing (scRNA-seq) in PBMCs (10x Genomics) to determine the cellular source of the 50-gene signature. We identified the presence of three genomic risk profiles in COVID-19 based on the 50-gene signature associated with low-, intermediate-, or high-risk of mortality and with significant differences in proinflammatory and profibrotic cytokines. Patients with COVID-19 in the high-risk group had increased expression of seven genes in CD14⁺HLA-DR^lowCD163⁺ monocytic-myeloid-derived suppressive cells (7Gene-M-MDSCs) and decreased expression of 43 genes in CD4 and CD8 T cell subsets. The loss of 7Gene-M-MDSCs and increased expression of these 43 genes in T cells was seen in survivors with post-COVID-19-ILD. On the contrary, patients with IPF had low expression of the 43 genes in CD4 and CD8 T cells. Collectively, we showed that a 50-gene, high-risk profile, predictive of IPF and COVID-19 mortality is characterized by a genomic imbalance in monocyte and T-cell subsets. This imbalance reverses in survivors with post-COVID-19-ILD highlighting genomic differences between post-COVID-19-ILD and IPF.NEW & NOTEWORTHY Changes in the 50-gene signature, reflective of increase in CD14⁺HLA-DR^lowCD163⁺ monocytes and decrease in CD4 and CD8 T cells, are associated with increased mortality in COVID-19. A reversal of this pattern can be seen in post-COVID-19-ILD, whereas its persistence can be seen in IPF. Modulating the imbalance between HLA-DR^low monocytes and T cell subsets should be investigated as a potential strategy to treat pulmonary fibrosis associated with severe COVID-19 and progressive IPF.

Turtle hepatocytes are a nonexcitable model for metabolic depression during low-temperature and/or anoxic overwintering conditions. Cytoskeletal structure and mitochondrial distribution are continuously modified in cells, and we hypothesized that metabolic depression would inhibit such processes as cell attachment and spreading and promote withdrawal of cell protrusions and peripheral mitochondria. After developing a methodology for culturing painted turtle hepatocytes, two-dimensional (2-D) area and maintenance of cell attachment after a media change were used as indicators of structural rearrangement and spreading/volume. These were measured after incubating cells at varying temperatures and with or without the inclusion of cyanide (chemical proxy for anoxia). Experiments were performed using cells from 22°C- or 5°C-acclimated turtles. Live-cell imaging was used to monitor the effect of cyanide exposure on the distribution of mitochondria. We also acclimated cultured cells from 22°C-acclimated turtles to 4°C in vitro and scored withdrawal of protrusions. Only cells isolated from 5°C-acclimated turtles and incubated at 4°C had reduced attachment to fibronectin substrate, but cyanide exposure had no effect. These cells also had a 30% smaller 2-D area than those from 22°C-acclimated turtles. There was no change in mitochondrial distribution during cyanide perfusion. Finally, 4°C acclimation in vitro resulted in the withdrawal of protrusions over 14 days. Taken together with the results from cells acclimated to low temperature in vivo, this suggests inhibition of structural rearrangement and protrusion stability by low temperature acclimation, but not cyanide exposure. Our cultured primary hepatocyte system will facilitate further study of the role of structural dynamics in reversible metabolic depression.NEW & NOTEWORTHY We have optimized a methodology for two-dimensional (2-D) culturing of primary western painted turtle hepatocytes and used this model to study the effects of cyanide and temperature on structural rearrangement, and the effect of cyanide on mitochondrial distribution. Our results suggest that low temperature acclimation, either in vivo or in vitro, inhibits cell protrusions and structural rearrangement. Acute cyanide exposure did not inhibit structural rearrangement or alter mitochondrial distribution.

Mechanosensation is essential for endothelial cell (EC) function, which is compromised in early-onset preeclampsia (EPE), impacting offspring health. The ion channels Piezo-type mechanosensitive ion channel component 1 (Piezo1) and transient receptor potential cation channel subfamily V member 4 (TRPV4) are coregulated mechanosensors in ECs. Current evidence suggests that both channels could mediate aberrant placental endothelial function in EPE. Using isolated fetoplacental ECs (fpECs) from early control (EC) and EPE pregnancies, we show functional coexpression of both channels and that Ca²⁺ influx and membrane depolarization in response to chemical channel activation is reduced in EPE fpECs. Downstream of channel activation, Piezo1 alone can induce phosphorylation of endothelial nitric oxide synthase (eNOS) in fpECs, while combined activation of Piezo1 and TRPV4 only affects eNOS phosphorylation in EPE fpECs. Additionally, combined activation reduces the barrier integrity of fpECs and has a stronger effect on EPE fpECs. This implies altered Piezo1-TRPV4 coregulation in EPE. Mechanistically, we suggest this to be driven by changes in the arachidonic acid metabolism in EPE fpECs as identified by RNA sequencing. Targeting of Piezo1 and TRPV4 might hold potential for EPE treatment options in the future.NEW & NOTEWORTHY This study shows Piezo-type mechanosensitive ion channel component 1 (Piezo1) and transient receptor potential cation channel subfamily V member 4 (TRPV4) coexpression and functionality within primary human fetoplacental endothelial cells (fpECs), mediating nitric oxide (NO) production and barrier integrity. In early-onset preeclampsia (EPE), fpEC channel functionality and coregulation are impaired, affecting Ca²⁺ signaling and endothelial barrier function. Combined channel activation significantly reduces endothelial barrier integrity and increases NO production in EPE. Changes in arachidonic acid metabolism are suggested as a key underlying factor mediating impaired channel functionality in EPE fpECs.

Amyotrophic lateral sclerosis (ALS) is characterized by dysfunction and loss of upper and lower motor neurons. Several studies have identified structural and functional alterations in the motor neurons before the manifestation of symptoms, yet the underlying cause of such alterations and how they contribute to the progressive degeneration of affected motor neuron networks remain unclear. Importantly, the short and long-term spatiotemporal dynamics of neuronal network activity make it challenging to discern how ALS-related network reconfigurations emerge and evolve. To address this, we systematically monitored the structural and functional dynamics of motor neuron networks with a confirmed endogenous C9orf72 mutation. We show that ALS patient-derived motor neurons display time-dependent neural network dysfunction, specifically reduced firing rate and spike amplitude, impaired bursting, but higher overall synchrony in network activity. These changes coincided with altered neurite outgrowth and branching within the networks. Moreover, transcriptional analyses revealed dysregulation of molecular pathways involved in synaptic development and maintenance, neurite outgrowth and cell adhesion, suggesting impaired synaptic stabilization. This study identifies early synaptic dysfunction as a contributing mechanism resulting in network-wide structural and functional compensation, which may over time render the networks vulnerable to neurodegeneration.

High-load resistance exercise (>60% of 1-repetition maximum) is a well-known stimulus to enhance skeletal muscle hypertrophy with chronic training. However, studies have intriguingly shown that low-load resistance exercise training (RET) (≤60% of 1-repetition maximum) can lead to similar increases in skeletal muscle hypertrophy as compared to high-load RET. This has raised questions about the underlying mechanisms for eliciting the hypertrophic response with low-load RET. A key characteristic of low-load RET is performing resistance exercise to, or close to, task failure, thereby inducing muscle fatigue. The primary aim of this evidence-based narrative review is to explore whether muscle fatigue may act as an indirect or direct mechanism contributing to skeletal muscle hypertrophy during low-load RET. It has been proposed that muscle fatigue could indirectly stimulate muscle hypertrophy through increased muscle fibre recruitment, mechanical tension, ultrastructural muscle damage, the secretion of anabolic hormones, and/or alterations in the expression of specific proteins involved in muscle mass regulation (e.g., myostatin). Alternatively, it has been proposed that fatigue could directly stimulate muscle hypertrophy through the accumulation of metabolic by-products (e.g., lactate), and/or inflammation and oxidative stress. This review summarizes the existing literature eluding to the role of muscle fatigue as a stimulus for low-load RET-induced muscle hypertrophy and provides suggested avenues for future research to elucidate how muscle fatigue could mediate skeletal muscle hypertrophy.

As a gas molecule, hydrogen sulfide (H₂S) exerts neuroprotective effects. Despite its recognized importance, there remains a need for a deeper understanding of H₂S's impact on vascular smooth muscle cells and its role in ischemic brain injury. This study employs encompassing cultured primary cerebral vascular smooth muscle cells, oxygen-glucose deprivation/reoxygenation model, in vitro vascular tone assessments, in vivo middle cerebral artery occlusion and reperfusion experimentation in male rats, and the utilization of ROCK₂ knockout, to unravel the intricate relationship between H2S and cerebrovascular diastolic function. Our findings show that RhoA activation induces heightened VSMC contraction, while the introduction of exogenous H₂S mitigates the relaxant effect of the middle cerebral artery in rats through the downregulation of both ROCK₁ and ROCK₂, with ROCK₂ exhibiting a more pronounced effect. Correspondingly, the attenuation of ROCK₂ expression yields a more substantial reduction in the protective impact of H₂S on cerebral blood flow, as well as learning and memory ability in ischemic injury, compared to the decrease in ROCK₁ expression. Moreover, we demonstrate that H₂S effectively mitigates the damage induced by oxygen-glucose deprivation/reoxygenation in male mouse primary vascular smooth muscle cells. This effect is characterized by enhanced cell proliferation, reduced lactate dehydrogenase leakage, elevated superoxide dismutase activity, and inhibited apoptosis. Notably, this protective effect is markedly diminished in cells derived from ROCK₂ knockout mice. Our study reveals that H₂S can relax cerebral vascular smooth muscle and ameliorate ischemic stroke injury by inhibiting the ROCK, with a particular emphasis on the role of ROCK₂.

Background: Parkinson's disease (PD) is an age-related neurodegenerative disorder. The pathological feature of PD is abnormal alpha-synuclein (α-syn) formation and transmission. Recent evidence demonstrates that α-syn preformed fibrils (α-syn PFF) can be detected in the serum of PD patients. The peripheral-blood α-syn PFF can cross the blood-brain barrier and aggravate neuronal damage, but the mechanism remains to be elucidated. Methods: We constructed the PD mouse models of different severity: the mild pathology (A53T ONLY) and the severe pathology (A53T+Brain FIB); this was followed by α-syn PFFs intravenous injection. Then, we used endothelium-specific Lag3 knockout mice (Lag3-ECs-CKO) to decrease the blood α-syn PFFs spreading. Results: We observed that intravenous transmission of α-syn PFFs significantly aggravated motor deficits, dopaminergic neuron loss, neuroinflammation and pathologic α-syn deposition in A53T ONLY, but not in A53T+Brain FIB. Blocking endothelial Lag3 endocytosis by Lag3-ECs-CKO decreased the blood α-syn PFFs spreading and improved the symptoms and pathogenesis of PD mice. Conclusions: Our findings reveal the role of peripheral-blood α-syn PFFs transmission in the mild pathology or early-stage PD and the mechanism of endothelial Lag3 endocytosis in the pathology of α-syn transmission. Targeting endothelial Lag3 to prevent α-syn from spreading from the blood to the brain may be a disease-modifying therapy in early-stage PD.

Glycogen synthase kinase 3 (GSK-3), a serine-threonine kinase with two isoforms (α and β) is implicated in the pathogenesis of type 2 diabetes mellitus (T2D). Recently, we reported the isoform-specific role of GSK-3 in T2D using homozygous GSK-3α/β knockout mice. Although the homozygous inhibition models are idealistic in a preclinical setting, they do not mimic the inhibition seen with pharmacological agents. Hence, in this study, we sought to investigate the dose-response effect of GSK-3α/β inhibition in the pathogenesis of obesity-induced T2D. Specifically, to gain insight into the dose-response effect of GSK-3 isoforms in T2D, we generated tamoxifen-inducible global GSK-3α/β heterozygous mice. GSK-3α/β heterozygous and control mice were fed a high-fat diet (HFD) for 16 wk. At baseline, the body weight and glucose tolerance of GSK-3α heterozygous and controls were comparable. In contrast, at baseline, a modest but significantly higher body weight (higher lean mass) was seen in GSK-3β heterozygous compared with controls. Post-HFD, GSK-3α heterozygous and controls displayed a comparable phenotype. However, GSK-3β heterozygous were significantly protected against obesity-induced glucose intolerance. Interestingly, the improved glucose tolerance in GSK-3β heterozygous animals was dampened with chronic HFD-feeding, likely due to significantly higher fat mass and lower lean mass in the GSK-3β animals. These findings suggest that GSK-3β is the dominant isoform in glucose metabolism. However, to avail the metabolic benefits of GSK-3β inhibition, it is critical to maintain a healthy weight.NEW & NOTEWORTHY The precise isoform-specific role of GSK-3 in obesity-induced glucose intolerance is unclear. To overcome the limitations of pharmacological GSK-3 inhibitors (not isoform-specific) and tissue-specific genetic models, in the present study, we created novel inducible heterozygous mouse models of GSK-3 inhibition that allowed us to delete the gene globally in an isoform-specific and temporal manner to determine the isoform-specific role of GSK-3 in obesity-induced glucose intolerance.

After the initial concepts of the constancy of the internal milieu or homeostasis, put forward by Claude Bernard and Walter Cannon, homeostasis emerged as a mechanism to control oscillations of biologically meaningful variables within narrow physiological ranges. This is a primary need in the central nervous system that is continuously subjected to a multitude of stimuli from the internal and external environments that affect its function and structure, allowing to adapt the individual to the ever-changing daily conditions. Preserving physiological levels of activity despite disturbances that could either depress neural computation or excessively stimulate neural activity is fundamental, and failure of these homeostatic mechanisms can lead to brain diseases. In this review, we cover the role and main mechanisms of homeostatic plasticity involving the regulation of excitability and synaptic strength from the single neuron to the network level. We analyze the relationships between homeostatic and Hebbian plasticity and the conditions under which the preservation of the excitatory/inhibitory balance fails, triggering epileptogenesis and eventually epilepsy. Several therapeutic strategies to cure epilepsy have been designed to strengthen homeostasis when endogenous homeostatic plasticity mechanisms have become insufficient or ineffective to contrast hyperactivity. We describe "on demand" gene therapy strategies, including optogenetics, chemogenetics, and chemo-optogenetics, and particularly focus on new closed loop sensor-actuator strategies mimicking homeostatic plasticity that can be endogenously expressed to strengthen the homeostatic defenses against brain diseases.

Asthma is one of the most common chronic respiratory diseases and is characterized by airway inflammation, increased mucus production, and structural changes in the airways. Recently, there is increasing evidence that the disease is much more heterogeneous than expected, with several distinct asthma endotypes. Based on the specificity of T cells as the best-known driving force in airway inflammation, bronchial asthma is categorized into T helper cell 2 (Th2) and non-Th2 asthma. The most studied effector cells in Th2 asthma include T cells and eosinophils. In contrast to Th2 asthma, much less is known about the pathophysiology of non-Th2 asthma, which is often associated with treatment resistance. Besides T cells, the interaction of myeloid cells such as monocytes/macrophages and mast cells with the airway epithelium significantly contributes to the pathogenesis of asthma. However, the underlying molecular regulation and particularly the specific relevance of this cellular network in certain asthma endotypes remain to be understood. In this review, we summarize recent findings on the regulation of and complex interplay between epithelial cells and the "nonclassical" innate effector cells mast cells and monocytes/macrophages in Th2 and non-Th2 asthma with the ultimate goal of providing the rationale for future research into targeted therapy regimens.